Final answer:
During the Persian Wars, the Greek city-states formed alliances and cooperated against the Persians, which they did not have after the Peloponnesian War.
Step-by-step explanation:
The agreement that the Greek city-states had during the Persian Wars that they did not have after the Peloponnesian War was a sense of unity and cooperation against a common enemy. During the Persian Wars, the Greek city-states formed alliances, such as the Delian League, to fight against the Persians. This alliance allowed them to collectively resist and ultimately defeat the Persian Empire.
However, after the Peloponnesian War, the Greek city-states became more divided and distrustful of each other. The war was a destructive and bitter conflict between Athens and Sparta, and it left the Greek city-states weakened and fractured. The alliances and cooperation that had been present during the Persian Wars were replaced by suspicion and rivalry.